Potter wasps, also named mason wasps, are found throughout the northern hemisphere, mainly in temperate regions. There are about 3000 species worldwide. Potter wasps measure between 9 to 20 millimeters in length. They are black with white, yellow, orange, or red markings.
Potter wasps are solitary and feed on flower nectar. They build mud nests for their eggs and larvae or use abandoned burrows of other insects. They stock the nests with paralyzed caterpillars and other grubs, which they seal in with mud. These are eaten alive by the wasp larvae.
The great potter wasp (Delta unguiculatum) in my photograph is a potter wasp from Europe. Its wingspan is 20-25 mm, males are slightly smaller than females.